Title : THE EFFECT OF STRESS ON MECHANICAL PROPERTIES OF ORDERING ALLOYS.

Descriptive Note : Final rept. Oct 62-Oct 65,

Corporate Author : WALES UNIV CARDIFF

Personal Author(s) : Arunachalam, V. S. ; Cahn, R. W.

Report Date : APR 1967

Pagination or Media Count : 201

Abstract : The influence of crystallographic order on the recrystallization properties was studied in copper-gold alloys, using X-ray diffraction, electron microscopy and microhardness measurements. The influence of order was found to be pronounced in retarding the onset of recrystallization for Cu3Au. At off-stoichiometric composition near Cu69/Au31, the formation of periodic antiphase structure was suppressed by the presence of a high dislocation density with cold-work. An interpretation based on a possible interaction between dislocations and domain boundaries explains the experimental observations. The second problem is the influence of compressive stress on the domain morphology of ordering CuAuI. Such 'stress-ordering effect' was first studied by Hirabayashi. Experiments were carried out on single crystals of CuAu in a vacuum dilatometer at various ordering temperatures and compressive stress levels. Added to its influence on orienting the domains (the stress-order effect), the applied compressive stress was found to modify the rate of ordering. The growth kinetics of ordering CuAu was studied in detail and the growth rates were calculated as functions of stress and orientation. The last part of this research is devoted to the study of the quench-ageing and strain-ageing of CuAu. Hardness measurements and micrographic observations were carried out on quench-ordered and strain-ordered CuAu.